What Does Zero Empirical Mean in Data Matrices?

[DUET]

Consider a data matrix, X, with zero empirical mean.

What is zero empirical mean?

Could someone please give me an example of such matrix?

 

[mathman]

Consider a data matrix, X, with zero empirical mean.

What is zero empirical mean?

Could someone please give me an example of such matrix?

It would help if would supply context. I presume empirical mean is a term for sample average, but I can't be sure.